Foods are often processed, i.e. cooked, in a thermoplastic film package by for example at least partially immersing the package in hot water or placing the package in a steam-heated environment. The processed food package may then be refrigerated until the processed food is to be consumed, and then reheated. Alternatively the processed food may be immediately removed from the thermoplastic film enclosure, as for example a casing or bag for consumption. Lustig et al U.S. Pat. No. 4,784,863, incorporated herein to the extent pertinent, describes such a cook-in system. Also described therein is a three layer film prepared by coextrusion, biaxial orientation to impart heat shrinkability, and then irradiation of the biaxially oriented film to widen the heat sealing temperature range and improve certain physical properties. The film may for example comprise an ethylene vinyl acetate (hereafter "EVA") inner layer, a vinylidene chloride copolymer oxygen barrier-core layer and an EVA outer layer.
It may be desirable to apply a modifier to the outer surface of the processed food. For example, if the food is poultry or ham, it may be desirable to impart smoke color and flavor to the cooked poultry or ham outer surface. This of course may be accomplished in a separate step by placing the processed food in a smoke house. For distribution this requires removal of a smoke-permeable enclosure from the smoked, processed food body and repackaging in an oxygen barrier type film enclosure for extended shelf life.
It would be desirable to provide a film article which can be used as an enclosure for processing enclosed food and also as a vehicle for simultaneously transferring modifiers such as liquid smoke to the food surface during processing.
Various problems have been encountered in attempts to provide such a film article. For example, powdered smoke concentrate was added to the inside surface of the inner EVA layer of an oxygen barrier type multilayer film of the type described in the aforementioned Lustig et al Patent. Hams processed in bags fabricated from this film had a moderate smoke flavor but the smoke color on the processed ham outer surface was highly non-uniform because the powder tended to accumulate in pockets on the ham surface during stuffing.
Another approach was to blend commercially available smoke-flavored polymer concentrates with the EVA resin used as the inner layer of the Lustig et al type coextruded multilayer film. Cook-in tests using bags fabricated from film with this inner layer blend did not transfer smoke color or flavor to the processed ham. Similarly there was no smoke color or flavor transfer to low fat meat bologna processed in casings prepared from this film.
Still another attempt to prepare a film with a transferable modifier involved melt blending a glycerine-based liquid smoke concentrate with the EVA resin used as the inner layer of the multilayer film. This caused the primary film discharged from the extruder to delaminate before biaxial orientation. Orientation was not possible.
A further approach was to mix equal weights of liquid smoke concentrate and powdered silica, then melt blending the liquid smoke-loaded powder with the EVA resin used as the film inner layer. Silica is of course a well-known absorbent. A multilayer film of the vinylidene chloride oxygen barrier type was produced having a smoke odor. However, very little smoke color or flavor was transferred to meat during cook-in tests using bags fabricated from this film.
A difficulty with these approaches was that for these tests the modifier was wood-derived smoke, and at extrusion temperatures for these particular multilayer films (about 350.degree. F.), the odor and taste components of the smoke are volatile and reactive, and do not survive extrusions in sufficient quantity to impart color or flavor to meat.
Accordingly, in other tests well-known absorbents such as starch, gypsum and thermoset crosslinked water soluble resin were blended with the EVA resin, and the multilayer film was coextruded. Then the film was contacted with liquid smoke for absorption thereby. However, the liquid smoke absorbency of these EVA-absorbent blend inner layer-type films was so low that transfer in the presence of water to contiguously associated surfaces for example food bodies, would be negligible.
An object of this invention is to provide an extruded film article containing a modifier such as a colorant or a fragrance or a colorant-fragrance such as liquid smoke, which is transferable from the film to a surface such as a food body outer surface enclosed by the film.
A further object of the invention is a method for making such a modifier-transferable film article.
Another object is to provide an enclosure such as a casing or bag, fabricated from the extruded film article, which will transfer the modifier to the outer surface of a body encased in the enclosure and in fluid association with the film inner surface.
A still further object is to provide a processable food package comprising a multilayer oxygen barrier type film enclosure containing a modifier, the enclosure being filled with processable food, wherein the modifier is transferable from the film enclosure to the food outer surface during insitu processing.
Still another object is a method for making a modified food package of the type hereinabove described.
Other objects and advantages of the invention will be apparent from the ensuing disclosure and appended claims. As will be explained hereinafter, this invention achieves all of the aforedescribed objects in an unexpected and efficient manner.